β-Carotene inhibition of chemically induced toxicity in vivo and in vitro

Abstract

In the past several years there has been a great deal of interest in the antioxidant β-carotene and other micronutrients for their protective potential against various toxic insults. Two studies concerning the protective effects of β-carotene, which were conducted in our laboratory, are reported here. The first involved the role of β-carotene in modifying two-stage skin tumorigenesis initiated by 7,12-dimethylbenz[ a]anthracene (DMBA) and promoted by phorbol 12-myristate 13-acetate (PMA, TPA). In this study, the protective effects of two types of dietary β-carotene, a beadlet formulation and crystalline β-carotene, were compared in two strains of mice (Skh:HR-1 and CR:ORL Sencar). Mice were maintained on food fortified with 3% β-carotene or on control diets. Mice receiving the β-carotene-supplemented diets had fewer tumours than mice in the control groups. However, only in the Skh strain of mice was this difference statistically significant. In the second study, an in vitro experiment, BALBc 3T3 mouse fibroblasts were used to determine β-carotene's accumulation in cells and the ability of these cells to metabolize β-carotene to vitamin A. This in vitro model was also used to show a β-carotene protective effect towards 8-MOP phototoxicity. These studies contributed to the increasing evidence of in vivo and in vitro protection by β-carotene against chemically induced toxicity.